BACKGROUND: Parathyroid diseases are related to parathyroid hormone (PTH) dysregulation by parathyroid cells or alteration of PTH function. They include hypoparathyroidism (PTH deficiency), pseudohypoparathyroidism (PTH resistance) and hyperparathyroidism (PTH excess). They are known to al- ter calcium metabolism and consequently bone health. Little is known about correlation between parathyroid diseases and metabolic syndrome. METHODS: Aim of this paper is to analyse the literature to identify the role of parathyroid diseases in bone health and metabolic syndrome.
RESULTS: Hypoparathyroidism and pseudohypoparathyroidism reduce bone remodelling, destroying mineral density with increase of fracture risk. Con- versely, hyperparathyroidism induces increase of bone reabsorption with increased fracture risk. Metabolic syndrome may negatively influence pa- rathyroid diseases and worsen bone health.
CONCLUSIONS: Available data confirm the role of parathyroid diseases in worsening bone health and highlight an important relationship between pa- rathyroid diseases, especially hyperparathyroidism, and metabolic syndrome, which is increasingly widespread.

Keywords: parathyroid hormone; hyperparathyroidism; hypoparathyroidism; bone; calcium; metabolic syndrome.